The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
The nervous system is responsible for an organism's perception of the world. It interprets information external to the organism and converts it into electrochemical signals that are then interpreted by the brain. Of particular importance for this application is the nervous system's response to pain and discomfort.
Pain is an unpleasant feeling that is caused by intense or damaging stimuli. Similar to the way an organism interprets tactile sensations, painful stimuli are received and then transmitted in the form of electrical signals to the brain where they are interpreted. When a stimulus is sufficient to cause actual or potential damage to the body, the brain interprets that stimulus as pain and creates a negative feeling that ranges in intensity depending on the severity of the stimulus.
Pain can be brief or enduring. In some, enduring pain can be disruptive to an otherwise normal life, leading to complications such as depression or job loss. Thus providing relief to sufferers of chronic pain is extremely important to improve that person's quality of life.
Efforts have been made in the past to develop ways to reduce pain by applying electrical signals to the body. For example, in U.S. Pat. No. 5,476,481 to Schöndorf, a transcutaneous electrical nerve stimulation (TENS) device is described. To use the device, electrodes are placed on opposite sides of the target tissue and an electrical signal is applied. One electrode is positive and the other is negative, and an electrical signal comprised of multiple super-imposed frequencies is applied to the tissue traveling from the positive to the negative electrode.
A problem with Schöndorf's system, however, is that electrical signals dissipate when passing through the body. The target tissue acts as a continuous resistor, and the farther the signal travels through the tissue, the more resistance it will encounter, thus reducing the effectiveness of the therapy. Schöndorf attempts to address this issue, and the issue of applying the signal to only one side of the tissue, by periodically reversing the polarity of the positive and negative electrodes. Unfortunately, the signal is still reduced as a function of depth leaving the most central areas of tissue without sufficient stimulation.
Another problem with Schöndorf is that applying a varying electrical signal directly to the body will not electromagnetically induce current in conductive materials within the body. An electrical signal will pass current through a target tissue, but will not achieve this effect. Thus, electrical signals are limited in terms of depth of penetration and inability to electromagnetically induce current in conductive materials within the body.
Thus, there is still a need for improved devices, systems, and methods to improve biological function.